1. Field of the Invention
The invention relates to antenna elements, generally, and particularly to an antenna element which provides arbitrary polarization and can be used to form a scanning array with a minimum number of elements while maintaining relatively constant active element input impedance over bandwidths approaching one octave.
2. Related Art
Crossed dipole (or turnstile antennas), folded dipoles and wire biconical antennas have been used alone and in arrays in a variety of communications and radar applications. C. Balanis in Antenna Theory Analysis and Design (1982) discloses at page 330 that biconical antennas have broadband characteristics useful in the VHF and UHF frequency ranges, but that the size of the solid shell biconical structure limits many practical applications. As a compromise, multielement intersecting wire bow tie antennas have been employed to approximate biconical antennas. Johnson and Jasik in the Antenna Engineering Handbook (1984) disclose crossed dipole antennas at page 28-10. Such antennas are used for producing circular polarization. Johnson at Jasik at page 4-12 also disclose biconical dipoles and, beginning at page 4-13, disclose the formation of folded dipoles by joining cylindrical dipoles at their ends and driving them by a pair of transmission lines at the center of one arm.
To date, however, there has been no disclosure of an antenna element that combines the desirable features of the biconical, crossed dipole and folded dipole antenna elements.